When adding or replacing a circuit breaker in a panel, it is imperative that the breaker is suitable for that panel and has proper I, II, and III and equivalent short‑circuit performance. Which option best captures this requirement?

• A. I, II, and III
• B. I and II
• C. II and III
• D. I, II, III and IV

Answer: (A)

The essential idea is that a breaker added to a panel must be listed for use with that specific panel and must provide the same level of short‑circuit capability the panel is designed to handle. Breakers are tested and paired with panels, and the panel’s listing specifies which short‑circuit performance levels (I, II, and III) it supports. The breaker should therefore offer I, II, and III ratings and provide equivalent short‑circuit performance so it does not become a weak point in the system. Adding a requirement beyond that, such as IV, isn’t part of the listed compatibility and could mean the breaker isn’t approved for that panel. Hence, the combination that matches the panel’s supported levels—I, II, and III—best captures the requirement.